Semiconductor devices are known to use oscillators to generate clock signals to control operation of these devices. In order for device using oscillator circuits to function properly, it is generally desirable that the frequency of the oscillator circuit's clock signal remain within specified tolerances over extended temperature changes. However, the ability to compensate for expected temperature changes is more difficult at low voltages such as voltages desirable during various low power modes of operation. Accordingly, an improved oscillator and methods of operating at low voltages would be advantageous.